Ethanol is one of the most used and abused drugs in our society and yet the cellular mechanisms that mediate its actions remain poorly understood. Numerous studies have suggested that the GABAA receptor/chloride ionophore, the primary inhibitory element in the mammalian CNS, may mediate at least some of the intoxicating actions of ethanol. Unfortunately, direct neurochemical support for this hypothesis has been inconsistent. Reasons for this variability are not known however recent evidence suggests that subtle differences in the subunit composition of GABAA receptors and/or the activity of protein kinase C may regulate the ethanol sensitivity of this complex. The proposal outlined in this application is a multidisciplinary project designed to assess the ethanol sensitivity of recombinant human GABAA receptors and to determine the factor(s) that may regulate this interaction. Defined human subunits will be expressed in murine fibroblasts. Using the whole- cell patch-clamp technique, we will resolve whether the function of this protein is enhanced by intoxicating concentrations of ethanol and if this enhancement is dependent on the subunit composition of the GABAA receptors. Furthermore, we will determine whether PKC-dependent phosphorylation of GABAA receptors, confirmed by immunoprecipitation and autoradiography, modulates the ethanol sensitivity of the complex. These studies will advance our present understanding of cellular mechanisms of ethanol action in humans and possibly identify novel factors that can modulate this interaction.